The use of refrigerant scroll compressors in motor vehicle air-conditioning systems is highly desirable, since this type of compressor has a robust structural design and can also be produced and used cost-effectively. Scroll compressors moreover operate radially to the inside, which results in a relatively short axial installation length for the compressor. An electrical refrigerant compressor can thus be designed without requiring any additional installation space compared to a mechanical refrigerant compressor.
The principle of compression of a scroll compressor consists of the fact that a orbiting scroll is moved in an oscillating manner within a fixed scroll such that a space forms between the flanks of the spirals, which becomes smaller from the external radial perimeter towards the center and therefore compresses the refrigerant gas that was collected at the periphery. The final compression pressure is obtained in an axial area of the spirals and the refrigerant gas is axially discharged at high pressure. For this purpose it is important that the orbiting scroll and the fixed scroll are sealed on their axial sides which lie one on top of the other, in order to prevent a radial cross flow of the refrigerant gas to the extent possible. For this reason, refrigerant scroll compressor design principles are used, which, by forming an intermediate pressure chamber, make it possible for the refrigerant gas to act on the orbiting scroll, so that a resulting force in the axial direction is created, whereby the orbiting scroll is pushed against the fixed scroll and thus seals the scrolls against one another.
A known problem with refrigerant scroll compressors consists of the fact that the oil return must be designed for process safety and at the same time must be able to develop a sufficient sealing force with reference to the orbiting scroll by controlling the intermediate pressure.
A scroll compressor with improved oil circulation and intermediate pressure control is known from U.S. Pat. Appl. Pub. No. 2009/0191081 A1. In this context, a scroll compressor is disclosed which realizes an oil return via the intermediate pressure chamber towards the suction side of the compressor.
This design from the prior art has the disadvantage, however, that the oil return and the intermediate pressure can only be poorly controlled.